The Canadian crustal stress database: Update to 2008

The Canadian Crustal Stress Database, originally compiled in 1985 and subsequently updated in 1987 and 1994, has been updated as of January 1, 2008. Here we describe the updated database. The 1994 database consisted of 1828 entries that spanned the depth range from near-surface to more than 30 km. These entries include stress measurements based on earthquake focal mechanisms (0-50 km depth), oil well breakouts (1-5 km), hydraulic fracturing (0-5 km), overcoring for engineering works (0-200 m), overcoring in mines (>200 m), and other surface geological phenomena (buckles, folds, popups, etc), and some geodetic (strain) measurements as aliases for stress. In 2008, a significant update more than 740 new entries was made. Approximately 90% of these new stress measurements are from western Canada with the remainder from eastern and northern Canadian earthquakes. They represent stress estimates from 548 regional moment tensor focal mechanisms, 16 Harvard moment tensor solutions, 172 P-nodal solutions, and 10 estimates from crustal shear-wave splitting. This updated database contributes to our understanding of the earthquake-generating crustal stress field in Canada and the cause(s) of stresses applied to the North American plate.